Methods of ACL reconstruction using interference screw fixation are described in U.S. Pat. Nos. 5,211,647 and 5,320,626, the entire disclosures of which are incorporated herein by reference. In general, these methods of ACL reconstruction involve drilling a tunnel through the tibia, drilling a closed tunnel (socket) into the femur, inserting a substitute ACL graft into the tunnels, and securing the grafts to the walls of the tibial and femoral tunnels using interference screws. Although interference screw attachment is generally secure, it is sometimes neither possible nor desirable to provide such fixation, particularly in the femoral tunnel. In revision situations, for example, where a previous reconstruction has been performed, placing a second femoral tunnel close to the previous tunnel may not be indicated.
A fixation technique which provides strong attachment of a graft in the femoral tunnel using a transverse implant is disclosed in U.S. Pat. No. 5,601,562, of common assignment with the present application, and incorporated by reference herein. The transverse implant is inserted through a loop in a tendon graft. A threaded portion of the implant screws into the bone as the implant is advanced with rotation into the repair site. The technique is disadvantageous, however, because the graft can become wrapped around the implant as it is rotated. In addition, this technique requires a forked insertion tool to lift the tendon graft into the femoral socket, and large tibial and femoral tunnels are needed to accommodate the forked insertion tool. As a result of the large tunnels, the graft can slide laterally and “wipe” back and forth along the fixation implant.
An improved method for loading tendons into a femoral socket is disclosed in U.S. Pat. No. 5,918,604, the entire disclosure of which is incorporated by reference herein. In this technique, a strand of suture or nitenol wire is drawn transversely across the femoral socket, and a loop of the strand is pulled down from the socket and out of the tibial tunnel. The tendon graft is passed through the loop, and the strand loop with tendon attached is lifted back into the femoral socket. A transverse implant is then advanced under the tendon graft, preferably by impact insertion to avoid wrapping of the tendon graft during insertion.
Although the technique disclosed in U.S. Pat. No. 5,918,604 is much improved over prior techniques and has come into widespread use, it does not provide for the use of a closed loop graft, such as a bone-tendon-bone graft or construct. Accordingly, there is a need for an improved fixation technique, particularly in cruciate ligament reconstructions, utilizing a bone-tendon-bone (BTB) graft, or construct.